I did this twice. I will learn eventually.
I sold a Coach Demi Liberty Vintage bag that I thought was too smal for me. I regreted sellling it so much I bought another one.
Then there was the Tye Dye Satchel in Denim that I sold. I was crazy! So I bought another in the Pink Tye Dye. These were 2 styles of bags that I knew I always would want. So they are here to stay now.
My coral Bottega Veneta cervo bag. It was a classic--I never used it after a year so I thought I should sell. Have regretted it ever since. It was a lovely shade of orange, though it looks more pink in the photos...
I have returner's remorse. I won a beautiful kate spade tracy bag on eBay and it had one small dent/wrinkle. I was too picky and returned it at Nordstrom (it had the tag on still, why the seller did not just return it - I don't know). I got more money from it but regret returning it. I never saw it in their handbag sections anytime after that.
I experienced this situation recently, I had bought a LV MC Speedy last year and thinking I wouldn't miss or use my 8 month old (still looked brand new) LV Mono Speedy 30, I gave it to my niece. So, while I was happy to give it to her, ( she loves it so much) everytime I'd see her, which is often I'd regret giving it to her because I realized I still love to have it in my collection. I solved the problem finally by buying the Mono Speedy 35!